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1. Charge-Transfer Complexation and
Excited-State Interactions in
Porphyrin-Silver Nanoparticle Hybrid
Structures
Sean Murphy, Libai Huang, and
Prashant V. Kamat
Radiation Laboratory, Department of
Chemistry and Biochemistry
University of Notre Dame, Notre Dame,
Indiana 46556, United States
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

2. Background
• Metallic nanoparticles possess localized surface plasmon resonance producing
a large electromagnetic field near the surface of the nanoparticle.
• Light-induced interaction between metallic nanoparticles and photoactive
molecules has been the subject of many recent studies.
• Adsorption of the dye and electron
transfer produce modulated optical
properties for dye-metal nanoparticle
composites.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

3. Absorption Properties
Red-shifted absorption band observed for the TAPP· · ·Ag nanoparticle complex.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

4. Surface Enhanced Resonance Raman
(SERRS) and Chemical Enhancement
A greater SERRS signal for TAPP than for two other free-base pophyrins with different
phenyl-substituents along with selective enhancement for TAPP Raman bands suggests
chemical enhancement.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

5. Excited State Interaction
The transient absorption spectrum of neat TAPP exhibits little change within a 40 ps
time window.
For TAPP· · ·Ag nanoparticle complex we observe the formation of a transient bleach
centered near 566 nm.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

6. Fast Charge Separation and Slower
Recombination
Fast quenching of TAPP fluorescence for the TAPP· · ·Ag nanoparticle complex indicates
charge separation.
Charge recombination leads to bleaching recovery.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}. Copyright {2011} American Chemical
Society

7. Summary
• Amine functional groups of TAPP lead to CT
complexation with Ag nanoparticles.
• CT complexation leads to observation of a red-
shifted absorption band and chemical
enhancement of the SERRS signal.
• Fast charge separation and subsequent
recombination are confirmed by femtosecond
time-resolved spectroscopies.
Reprinted with permission from {J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769}.
Copyright {2011} American Chemical Society

8. Thank you for viewing the slideshow!
This work can be found in the Journal of Physical Chemistry C
(DOI: 10.1021/jp205711x)
J. Phys. Chem. C, 2011, 115 (46) pp 22761 - 22769
Additional information about the Kamat research group can be
found at www.nd.edu/~pkamat
Additional information about the Huang research group can be
found at http://www.nd.edu/~lhuang2/Libai_Huang/Home.html